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<!DOCTYPE HTML> <html lang="ja" > <head> <meta charset="UTF-8"> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> <title>フォームの扱い · Vuex</title> <meta http-equiv="X-UA-Compatible" content="IE=edge" /> <meta name="description" content=""> <meta name="generator" content="GitBook 3.2.3"> <link rel="stylesheet" href="../gitbook/style.css"> <link rel="stylesheet" href="../gitbook/gitbook-plugin-prism/prism.css"> <link rel="stylesheet" href="../gitbook/gitbook-plugin-search/search.css"> <link rel="stylesheet" href="../gitbook/gitbook-plugin-theme-vuejs/vue.css"> <meta name="HandheldFriendly" content="true"/> <meta name="viewport" content="width=device-width, initial-scale=1, user-scalable=no"> <meta name="apple-mobile-web-app-capable" content="yes"> <meta name="apple-mobile-web-app-status-bar-style" content="black"> <link rel="apple-touch-icon-precomposed" sizes="152x152" href="../gitbook/images/apple-touch-icon-precomposed-152.png"> <link rel="shortcut icon" 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data-path="strict.html"> <a href="strict.html"> 厳格モード </a> </li> <li class="chapter active" data-level="1.10" data-path="forms.html"> <a href="forms.html"> フォームの扱い </a> </li> <li class="chapter " data-level="1.11" data-path="testing.html"> <a href="testing.html"> テスト </a> </li> <li class="chapter " data-level="1.12" data-path="hot-reload.html"> <a href="hot-reload.html"> ホットリローディング </a> </li> <li class="chapter " data-level="1.13" data-path="api.html"> <a href="api.html"> API リファレンス </a> </li> <li class="divider"></li> <li> <a href="https://www.gitbook.com" target="blank" class="gitbook-link"> GitBookで公開 </a> </li> </ul> </nav> </div> <div class="book-body"> <div class="body-inner"> <div class="book-header" role="navigation">  <h1> <i class="fa fa-circle-o-notch fa-spin"></i> <a href="." >フォームの扱い</a> </h1> </div> <div class="page-wrapper" tabindex="-1" role="main"> <div class="page-inner"> <div id="book-search-results"> <div class="search-noresults"> <section class="normal markdown-section"> <h1 id="フォームの扱い">フォームの扱い</h1> <p>厳格モードで Vuex を使用するとき、Vuex に属する状態の一部で <code>v-model</code> を使用するのは少しトリッキーです:</p> <pre class="language-"><code class="lang-html"><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>input</span> <span class="token attr-name">v-model</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>obj.message<span class="token punctuation">"</span></span><span class="token punctuation">></span></span> </code></pre> <p><code>obj</code> がストアからオブジェクトを返す算出プロパティ (computed property) と仮定すると、<code>v-model</code> は input でユーザーが入力するとき、直接 <code>obj.message</code> を変更します。厳格モードでは、この変更は明示的に Vuex のミューテーションハンドラ内部で処理されていないため、エラーを投げます。</p> <p>それに対処するための "Vuex way" は、<code><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>input</span><span class="token punctuation">></span></span></code> の値をバインディングし、<code>input</code> または <code>change</code> イベントでアクションを呼び出すことです:</p> <pre class="language-"><code class="lang-html"><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>input</span> <span class="token attr-name">:value</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>message<span class="token punctuation">"</span></span> <span class="token attr-name">@input</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>updateMessage<span class="token punctuation">"</span></span><span class="token punctuation">></span></span> </code></pre> <pre class="language-"><code class="lang-js"><span class="token comment" spellcheck="true">// ...</span> computed<span class="token punctuation">:</span> <span class="token punctuation">{</span> <span class="token operator">...</span><span class="token function">mapState</span><span class="token punctuation">(</span><span class="token punctuation">{</span> message<span class="token punctuation">:</span> state <span class="token operator">=</span><span class="token operator">></span> state<span class="token punctuation">.</span>obj<span class="token punctuation">.</span>message <span class="token punctuation">}</span><span class="token punctuation">)</span> <span class="token punctuation">}</span><span class="token punctuation">,</span> methods<span class="token punctuation">:</span> <span class="token punctuation">{</span> updateMessage <span class="token punctuation">(</span>e<span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token keyword">this</span><span class="token punctuation">.</span>$store<span class="token punctuation">.</span><span class="token function">commit</span><span class="token punctuation">(</span><span class="token string">'updateMessage'</span><span class="token punctuation">,</span> e<span class="token punctuation">.</span>target<span class="token punctuation">.</span>value<span class="token punctuation">)</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> </code></pre> <p>ミューテーションのハンドラは以下のようになります:</p> <pre class="language-"><code class="lang-js"><span class="token comment" spellcheck="true">// ...</span> mutations<span class="token punctuation">:</span> <span class="token punctuation">{</span> updateMessage <span class="token punctuation">(</span>state<span class="token punctuation">,</span> message<span class="token punctuation">)</span> <span class="token punctuation">{</span> state<span class="token punctuation">.</span>obj<span class="token punctuation">.</span>message <span class="token operator">=</span> message <span class="token punctuation">}</span> <span class="token punctuation">}</span> </code></pre> <h3 id="双方向算出プロパティ">双方向算出プロパティ</h3> <p>確かに、上記の例は単純な <code>v-model</code> と ローカルステートよりもかなり冗長で、<code>v-model</code> のいくつかの有用な機能が使えません。代わりに、セッターで双方向算出プロパティを使うアプローチがあります。</p> <pre class="language-"><code class="lang-html"><span class="token tag"><span class="token tag"><span class="token punctuation"><</span>input</span> <span class="token attr-name">v-model</span><span class="token attr-value"><span class="token punctuation">=</span><span class="token punctuation">"</span>message<span class="token punctuation">"</span></span><span class="token punctuation">></span></span> </code></pre> <pre class="language-"><code class="lang-js">computed<span class="token punctuation">:</span> <span class="token punctuation">{</span> message<span class="token punctuation">:</span> <span class="token punctuation">{</span> <span class="token keyword">get</span> <span class="token punctuation">(</span><span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token keyword">return</span> <span class="token keyword">this</span><span class="token punctuation">.</span>$store<span class="token punctuation">.</span>state<span class="token punctuation">.</span>obj<span class="token punctuation">.</span>message <span class="token punctuation">}</span><span class="token punctuation">,</span> <span class="token keyword">set</span> <span class="token punctuation">(</span>value<span class="token punctuation">)</span> <span class="token punctuation">{</span> <span class="token keyword">this</span><span class="token punctuation">.</span>$store<span class="token punctuation">.</span><span class="token function">commit</span><span class="token punctuation">(</span><span class="token string">'updateMessage'</span><span class="token punctuation">,</span> value<span class="token punctuation">)</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> <span class="token punctuation">}</span> </code></pre> </section> </div> <div class="search-results"> <div class="has-results"> <h1 class="search-results-title"><span 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